package leetcode;

/**
 * 动态规划：不同子序列
 */
public class Solution66 {
    public int numDistinct(String s, String t) {
        //求出数组长度
        int length1 = s.length();
        int length2 = t.length();
        //定义dp数组
        int[][] dp = new int[length1+1][length2+1];
        for(int i = 0;i < s.length() + 1;i++){
            dp[i][0] = 1;
        }
        //for循环遍历
        for(int i = 1;i < s.length() + 1;i++){
            for(int j = 1;j < t.length() + 1;j++){
                if(s.charAt(i-1) == t.charAt(j-1)){
                    dp[i][j] = dp[i-1][j-1] + dp[ i- 1][j];
                }else{
                    dp[i][j] = dp[i - 1][j];
                }
            }
        }
        return dp[s.length()][t.length()];
    }
}
